The couple - who met on the set of the 2014 movie 'Fantastic Four' - are set to tie the knot after Jamie popped the question, Kate's representative confirmed to E! News.

Kate, 33 and Jamie, 30, went public with their romance in May 2015, when they were spotted going for an affectionate stroll together in Malibu, California.

A source said at the time: "They 100 per cent looked like they were a couple. They had their arms around one another the whole time and they looked totally in love.

(Image: Twitter/Kate Mara)

"They were holding each other the whole time. They didn't let go. They were hugging and walking with their arms around each other and were totally focused on one another. They were walking the dog, but even when the dog was running off they were still focused on each other."

Later that month they were seen holding hands at the Met Gala in New York. Jamie split from Evan Rachel Wood, with whom he has a young son, in 2014 after just 19 months of marriage.

Jamie Bell and Kate Mara (Image: WENN.com)

And she has since referred to him as the "love of her life", insisting they will always have a special bond because of their son.

Kate, who flashed her rock on Twitter, said: "Jamie's lovely. He was the love of my life."

Remembering her candlelit birth, she said: "It was a psychedelic experience. I felt like I was hitting every corner of the room. Everything was vibrating."